glibc/sysdeps/x86/bits/byteswap-16.h
2013-06-07 22:24:35 +00:00

50 lines
1.7 KiB
C

/* Macros to swap the order of bytes in 16-bit integer values.
Copyright (C) 2012-2013 Free Software Foundation, Inc.
This file is part of the GNU C Library.
The GNU C Library is free software; you can redistribute it and/or
modify it under the terms of the GNU Lesser General Public
License as published by the Free Software Foundation; either
version 2.1 of the License, or (at your option) any later version.
The GNU C Library is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
Lesser General Public License for more details.
You should have received a copy of the GNU Lesser General Public
License along with the GNU C Library; if not, see
<http://www.gnu.org/licenses/>. */
#ifndef _BITS_BYTESWAP_H
# error "Never use <bits/byteswap-16.h> directly; include <byteswap.h> instead."
#endif
#ifdef __GNUC__
# if __GNUC__ >= 2
# define __bswap_16(x) \
(__extension__ \
({ unsigned short int __v, __x = (unsigned short int) (x); \
if (__builtin_constant_p (__x)) \
__v = __bswap_constant_16 (__x); \
else \
__asm__ ("rorw $8, %w0" \
: "=r" (__v) \
: "0" (__x) \
: "cc"); \
__v; }))
# else
/* This is better than nothing. */
# define __bswap_16(x) \
(__extension__ \
({ unsigned short int __x = (unsigned short int) (x); \
__bswap_constant_16 (__x); }))
# endif
#else
static __inline unsigned short int
__bswap_16 (unsigned short int __bsx)
{
return __bswap_constant_16 (__bsx);
}
#endif